The Big Bang Theory SeasonAt the end of the season, he leaves Pasadena for time to figure out who he is and what he wants after all the changes happening in his life, making his way to Arizona at the start of season 8. Amy asks for some time to think about their relationship just when Sheldon was considering proposing.The Big Bang Theory Season of the American sitcom The Big Bang Theory first aired on CBS with a one-hour premiere on Monday, September 22, 2015.